Navigator&#39;s calculating instrument.



E. HILL, JB. NAVIGATOB.S OALGULATING INSTRUMENT.

v APPLICATION FILED APB.. 8, 1909.

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Patented Jan. 11,1910.

/Nvf/v roR EBENEZEB HILL, JB., OF NORWALK, CONNECTICUT.

NAVIGATOBS GALCULATING INSTRUMENT.

Bpecication o! Letters Patent.

Patented Jan. 11, 1910.

Application filed April 8, 1909. Serial No. 488,553.

To all rwhom 'it may concern:

Be it known that I, EBENEZER HILL, Jr., a citizen of the United States, residing at Norwalk, in the county of Fairfield and State of Connecticut, have invented a new and useful Improvement in Navigators Calculating Instruments, of which the followin is a specification.

his invention relates to an instrument which is provided for the purpose of aiding a navigator in determining the actual compass course of a vessel.

The object of the invention is the production of an instrument which will indicate the variations of the compass needle from true north and south, the deviations of the needle due to local causes and ship influences, and the allowances made for wind and tide, and will point to the correct com- A pass course, the computations of which are entirely obtained by simple mechanical manipulations of the various dials and pointers of the instrument.

This instrument rovides a visible record of the Yallowance or variation, deviation, wind and tide, which may be quickly comA puted, and instantly read by any seaman capable of reading a compass card, and readily inspected and verified by any otiicer at a glance. The employment of this instrument economizes t1me, particularly when the courses are frequently changed, and the easterly or westerl deviation of the needle must be correcte for every course, and when, as often happens, the allowance for easterly or westerly variation must be corrected several times during a voyage; and avoids many arithmetical calculations for variation, deviation, wind and tide, involving addition and subtraction, with the incident chances of errors in signs, which may lead to serious mistakes and lamentable accidents.

Figure 1 of the accompanying drawings shows a plan of an instrument which embodies this invention. Fig. 2 shows a diametrical section of the same.

The instrument shown, has a di'sh shaped case 1, which may be made of brass, or any.

other convenient material. F astened over the top of the case is a cover 2, which is preferably plate glass, or some similar transparent material.

Secured to, or marked on, the inside of the bottom of the case is a dial, card or rose 3, which has the letters N. S. E. W'., indicating the cardinal points of the comass. Inside of the circle with the cardinal letters, this fixed rose has letters, figures and lines indicating the minor points of the compass. Outside of the cardinal letters, the fixed rose is graduated and numbered to indicate the usual degrees of the con"- ass.

p Encircling the fixed rose, and loosely mounted on a slightly higher plane in the case, is a rin r with an annular rose 4 having the letters N. S. E. W., indicating the cardinal compass points, and graduations and numbers indicating the usual degrees of the compass. This ring has a stud 5, which projects from its back through a slot 6 in the bottom of the case, and turningon the threaded end of this stud is a nut 7. Vheu this nut is loosened, the ring may be rotated about 90 degrees, but when the nut is screwed up on the stud against the bottom of the ease, the ring is held fast. The can dinal points on the movable annular rose are arranged reversely to the cardinal points on the fixed central rose, that is, N is ad- 'acent to S, Sis adjacent to N, E 1s adjacent to lV, and W is adjacent to E.

Secured to or marked on the case, outside of the movable annular rose is a segmental rose 8, with graduations and figures indicating compass degrees from zero to 45 on each side of zero. On the left hand side of this outer fixed graduated arc or segmental rose, are the words Easterly variation, and on the right hand side are the words llfesterly variation Extending through the center of the case, of the instrument illustrated, is a tubular arbor 9, which on its lower end has a finger piece 10, by which it may be turned. Pro- ]ecting from this arbor over the fixed central rose, referablv to the degree graduations mar 'ed on that rose, is a needle or pointer 11, and upon the tail 12 of this pointer is a scale marked in degrees from zero, at the center, to 25 degrees on each side'. The degrees on this tail on one side of zero are marked Westerl deviation, and on the other side Easterly deviation.

In the form of instrument shown, there is an arbor 13, extending through the tubular arbor at the center. This arbor has a finger piece 14, by which it may be turned, on its outer end, and a pointer 15 on its inner end. The pointers are desirably diii'erent colors, preferably black and red, so that they may e readily distinguished.

In uslng this instrument, the movable ring with the annular compass rose is loosened and turned until its needle point cr N, is opposite the degree on the outer scale, or segmental rose, corresponding to the known westerly or easterly variation as the case may be, of the compass needle from the true north, which degree is taken from the data given on the navigation charts. For example, if the compass needle, at the time, varies 15 degrees westerly, the needle point, or N, of the movable annular compass rose is moved opposite to the degree indicating 15 degrees westerly variation, as shown in Fig. 1. After the movable compass rose is fastened in this position, by tightening the nut on the bottom of the instrument, the movable ointer l1, if there is'no deviation due to ocal causes aboard shi is turned by the finger piece on the bacli, until the zero point on its tail is opposite the degree on the now tixed annular rose, which indicates the desired true course1 as determined from the chart. If there is no deviation, and the true course is east, zero on the tail is turned o posite to E, on the annular rose, which has been adjusted to allow for the required variation. Under these circumstances, the needle to which the tail piece is attached, points to S. 75 degrecs E on the fixed central rose. If there 1s a westerly deviation of 10 degrees, the degree marked 10 degrees westerly deviation upon the tail piece 1s moved opposite to E, o the annular compass rose, and then We read from the point of the needle 11 on the lixed central compass rose, the compass course S 65 degrees E, as shown in the drawing. It' the known course is such that besides the allowances for variation and deviation, allowance must be made for tide, or the influence of wind, `the pointer 15, which is preferably red, is then adjusted either side of the magnetic course, as indicated by the black pointer, to indicate the allowance in degrees thus to be made for tide and wind. This red pointer is then the one from which the helmsman reads the course to follow.

The invention claimed is:

1. A navigators calculating instrument,

having a case with a fixed central compass rose, a movable annular compass rose encirclmg the fixed rose, a fixed variation scale outside of the annular rose, a pointer movable over the fixed central rose, and a deviation scale carried by the tail of the ointer and movable adjacent to the graduatlons on the annular rose.

2. A navigators calculating instrument, having a case with a fixed central compass rose, a movable annular compass rose encircling the fixed rose, a fixed variation scale outslde of the annular rose, a pointer movable over the lixed central rose, a deviation scale carried by the tail of said pointer and movable adjacent to the graduations on the annular'` rose, and a second pointer movable over the fixed rose. v

3. A navigators calculating instrument having a case with a fixed central compass rose, an annular com ass rose movable on the case at a higher evel than the central compass rose which it encircles, a variation scale fixed to the case outside of the annular rose, a pointer su ported by the case and movable over the xed rose and a segment fastened to and movable with the pointer on a plane substantially the same as that of the annular rose, said segment having a deviation scale movable in proximity to the graduations of the annular, rose.

4. A navigators calculating instrument having a case, a fixed central compass rose, an annular compass rose encircling the fixed rose, a stud projecting from the back of the annular rose through the bottom of the case, a clamp nut for moving and fastening the annular rose, a variation scale fixed to the case outside of the annular rose, a spindle extendin through the bottom of the case, a pointer tstened to the spindle and movable over the fixed rose, a se ment mounted on the spindle, said segment aving a deviation scale movable adjacent to the graduations of the annular rose, and means attached to the bottom end of the spindle for turning the same.

5. A navigators calculating instrument having a case, a fixed central compass rose, an annular compass rose encircling the fixed rose, a stud projecting from the back of the annular rose through the bottom of the case, a clamp nut for moving and fastening the annular rose, a variation scale fixed to the case outside of the annular rose, a spindle extendin through the bottom of the case, a pointer astened to the spindle and movable over the fixed rose, a se ment mounted on the spindle, said se ent aving a deviation scale that is movab e adjacent to the graduations of the annular rose, means attached to the bottom end of the spindle for turning the same, a s indle extending through the first mentioned spindle, means on the lower end of the central spindle for turning the same, and a pointer fastened to the upper end of the central spindle and movable over the fixed rose. l

6. A navigators calculating instrument, the pointer and movable adjacent to the having a casel with a fixed central compass graduations on the annular rose. rose, a movab e annular com ass rose encircling the xed rose, means or moving the EBENEZER HILL JR' annular rose about the central rose, a pointer Witnesses: movable over the central rose, and a seg- H. R. WILLIAMS, mental deviation scale carried by the tail of JOSEPHINE M. STREMPFER. 

